From owner-freebsd-hackers Tue Jan 28 11:36:36 1997 Return-Path: Received: (from root@localhost) by freefall.freebsd.org (8.8.5/8.8.5) id LAA05085 for hackers-outgoing; Tue, 28 Jan 1997 11:36:36 -0800 (PST) Received: from root.com (implode.root.com [198.145.90.17]) by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id LAA05080 for ; Tue, 28 Jan 1997 11:36:34 -0800 (PST) Received: from localhost (localhost [127.0.0.1]) by root.com (8.7.6/8.6.5) with SMTP id LAA16507; Tue, 28 Jan 1997 11:36:05 -0800 (PST) Message-Id: <199701281936.LAA16507@root.com> X-Authentication-Warning: implode.root.com: Host localhost [127.0.0.1] didn't use HELO protocol To: Petri Helenius cc: hal@vailsys.com, hackers@freebsd.org Subject: Re: best mtu for lo0? In-reply-to: Your message of "Tue, 28 Jan 1997 19:45:36 +0200." <199701281745.TAA25913@silver.sms.fi> From: David Greenman Reply-To: dg@root.com Date: Tue, 28 Jan 1997 11:36:05 -0800 Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk > > Petri Helenius wrote: > > > > > What's your lo0 MTU? If it's the 16384 that some > > > non-tcp-knowledgeable person put in sometime in the past > > > I think what you are seeing is called "TCP deadlock" which appears when > > > window size is equal or smaller than the MTU. This makes TCP to be ... > > Is this correct? I notice 2.1.6-R sets MTU for lo0 to 16384. Should > > this be reduced to 1500? Will it affect performance of aliased IP > > addresses, for which a static route through lo0 is usually specified? > >Want me to comment on this (I'm not on the hackers list any longer >though)? > >The above still stands true that if you set your TCPWIN < MTU you'll >experience TCP 'deadlock' which ends up being of horrible performance. Pete is likely correct that window < MTU is a problem (that's obvious, right?), but he's wrong that this is occuring in recent versions of FreeBSD. The send/receive windows are set to 3*MTU, and for lo0 this is 49152 bytes. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project